C ++构造函数初始化堆栈中的非基本成员变量

Question

I've a basic question about C++ constructors.

Let's say that I have a class definition something like this:

class Project {
public:
    int time;
    std::vector<Task> tasks;

    Project();
};

I want to initialize this vector in my source file, however I'm not sure about the correct and efficient way to do this.

Project::Project() {
    time = 0;
    tasks = std::vector<Task>();
}

Is this a correct way to initialize object in the stack?

Answer 1

Vectors can use custom allocators, so you may be able to use a vector class specialized for a custom allocator (like this one ).

However, you cannot use the stack of the constructor itself, as it becomes invalidated after the constructor finishes. You either need to allocate the memory in the object itself (in the linked example, make the arena a member of the class) or receive it as a parameter to the constructor.